You just have to test things. Test formats, position, colours everything. What works on one site may not work on another. There really is no one size fits all tip
Short answer: You need ads, that are relevant to your content and your content must serve as a teaser for the products typically advertised (e.g.: If you are writing cellphone reviews, you should have ads for hardware stores selling cellphones on your site). More info on this: See my signature.
Check out the google heat map for the best places to put your adsense ads. If your ads are in the best place mixed with lots of traffic you should be able to get a decent ctr
There are two thing you can do to imrpove your CTR 1. Optimize your Ads format (including size, font, colour and etc) and placement. Try to change format and placement, then monitor for few week to find the best 2. Content - This is always being ignored. Content might cause your visitor feel interested on more about the topic, then it increase the chances to get clicked
Get some visitor that have addicted for clicking ads hahaha... its a new method for me to increase CTR.
Best ways is that keep changing ads positions and color of themes . By doing this sometime we get good combination and increased CTR also .